Professor McGonagall is setting up timetables, depending on the necessary OWLs which students need to continue with their NEWTs. She makes Neville feel better about himself. Harry apparently can still become an Auror since Slughorn will certainly accept an "Exceeds Expectations" to take Potions, Snape would have required an "Outstanding".

Harry receives a parchment from Dumbledore with the date and time of their first private lesson.

The three have their first Potions lesson by Professor Slughorn. The dungeon already has some full cauldrons. Harry and Ron do not have his Advanced Potion-Making by Libartius Borage copy since he never thought he would continue Potions. Slughorn lends them 2 copies from a corner cupboard. The potions which Slughorn had already prepared contain among them Veritaserum, Polyjuice Potion and Amortentia, a love potion. Hermione recognizes three of them and Slughorn asks her if she possibly is related to Hector Dagworth-Granger, who founded the Most Extraordinary Society of Potioneers. Slughorn says Amortentia is possibly the most powerful potion in the room. The final potion is Felix Felicis, liquid luck. He is offering a tiny bottle as a prize for the student who brews the best potion that day. They need to create the Draught of Living Death. Draco asks Slughorn if he knew his grandfather Abraxas Malfoy. In Harry's borrowed copy of Advanced Potion-Making the previous owner has made annotations, following the directions in a desperate wish to catch up. He crushes Sopophorous Beans with a flat side of a silver dagger, as indicated in the scribbles by the previous owner, instead of crushing them which the original text of the lesson book dictates, and amazingly this works better. Harry follows more notes and he gets the best result. Slughorn, who does not know harry followed non-original instructions of the scribbles in the book, thinks Harry might have inherited Lily´s potion skills, and awards Harry the bottle of Felix Felicis.

After class he also tells Ron what he did. Hermione does not really agree with what Harry did, and neither does Ginny who at that moment hears Harry saying that he has been "taking orders from something someone wrote in a book" (like she did a few years ago with Riddles diary, having disastrous consequences). Hermione uses a ¤ Specialis Revelio to see if the book has some hidden magical properties, but it shows nothing. When Harry retrieves the book, he notices a scribble on the bottom of the back cover though, saying "This Book is Property of the Half-Blood Prince"